There are many existing and potential industrial and commercial applications for intelligent agents in the literature. The very challenging issue for these applications is to "do what intelligent agents should do". The BDI (beliefs, desires, intentions) architecture is presented to solve this challenge, and it has attracted much attention. The main difficulty for this architecture is the formalization problem. In this paper, we discuss the "procedure descriptive framework", which is a method for formalizing the BDI architecture. We present decision models for intelligent agents in this framework. This research provides a technique for online agents to form beliefs and make decisions according to the current uncertain environment.